Systems and methods for containers with locking lug and recess

ABSTRACT

Thermoformed locking assembly comprising a first web portion including locking lug having lug undercut defining a cantilevered lug ledge having lug engaging surface, second web portion including locking recess having recess undercut defining an opposing recess ledge having recess engaging surface and a lug stop opposite the recess undercut. Locking recess configured to receive locking lug and lug stop configured to position locking lug in locking recess with the lug engaging surface in engagement with the recess engaging surface when first web portion is moved towards second web portion.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a divisional of U.S. patent application Ser.No. 15/851,486 filed Dec. 21, 2017, which claims priority to U.S.Provisional Application Ser. No. 62/437,649 filed Dec. 21, 2016, thecontents of each of which are incorporated herein by reference in theirentireties.

FIELD OF THE APPLICATION

The disclosed subject matter relates to a thermoformed locking assembly,and articles, such as a container, having a thermoformed lockingassembly.

DESCRIPTION OF THE RELATED ART

Articles, such as containers, are frequently made by thermoforming a webof material. Articles so produced can, for example, be used forshipping, storing, preparing and/or serving a wide range of food items,such as an egg carton for eggs or a cake container for cakes. It isbeneficial, or perhaps necessary, for such thermoformed containers to becapable of being locked closed.

Although various locking assemblies are known, there remains a need fora thermoformed locking assembly and articles, such as a container,having a thermoformed locking assembly that can be securely lockedclosed, but readily opened when desired.

SUMMARY

The purpose and advantages of the disclosed subject matter will be setforth in and apparent from the description that follows, as well as willbe learned by practice of the disclosed subject matter. Additionaladvantages of the disclosed subject matter will be realized and attainedby the methods and systems particularly pointed out in the writtendescription and claims hereof, as well as from the appended drawings.

To achieve these and other advantages, and in accordance with thepurpose of the disclosed subject matter, as embodied and broadlydescribed, the disclosed subject matter includes a thermoformedcontainer including a base having a base flange and a lid having a lidflange. The lid is configured to be moved relative to the base between aclosed position and an open position. The lid flange is adjacent to thebase flange when in the closed position. At least one of the base flangeor the lid flange is formed to include a locking lug having a lugundercut defining a cantilevered lug ledge having a lug engagingsurface. The other of the base flange or lid flange is formed to includea locking recess having a recess undercut defining an opposing recessledge having a recess engaging surface and a lug stop opposite therecess undercut. The locking recess is aligned to receive the lockinglug and the lug stop is configured to position the locking lug in thelocking recess such that the lug engaging surface is in engagement withthe recess engaging surface to define a locking assembly when the baseand lid are in the closed position.

Additionally, and as embodied herein, the lid can be hingedly connectedto the base by a hinge. The hinge can be disposed on an opposite side ofthe container as the locking lug and locking recess. Alternatively, asfurther embodied herein, the base and the lid can be two separatemembers to allow removal of the lid when the lid is moved to the openposition.

Furthermore, and as embodied herein, a minimum closing force can beapplied to move the lid into the closed position with the lug engagingsurface in engagement with the recess engaging surface, and a minimumopening force can be applied to move the lug engaging surface out ofengagement with the recess engaging surface. The minimum opening forcecan be greater than the minimum closing force. The cantilevered lugledge and the opposing recess ledge can each have an outer edge, and atleast one outer edge can be chamfered or rounded to maintain the desiredminimum closing force required to move the lid into the closed positionwith the lug engaging surface in engagement with the recess engagingsurface.

In addition, and as embodied herein, the locking lug can includestiffening ribs along two sides of the locking lug. The locking recesslikewise can include stiffening ribs along two sides of the lockingrecess. As additionally embodied herein, the locking lug can begenerally L-shaped in cross section. Likewise, the locking lug can beprovided with a single-sided configuration, wherein a lug undercut isprovided only on one side of the locking lug. Similarly, the lockingrecess can be single-sided with the recess undercut on one side of thelocking recess. In this manner, the locking lug and recess can beprovided in a relatively small space, so as to be incorporated oncontainers of smaller size and reduced web thickness, withoutcompromising the integrity of the minimum closing and opening forces asdesired. As further embodied herein, the locking lug can include a rampto reduce stack height.

In accordance with another aspect of the disclosed subject matter, amethod of forming a thermoformed locking assembly, or an article, suchas a container, having such locking assembly is provided. Thethermoformed locking assembly includes a locking lug having an undercutdefining a cantilevered lug ledge having a lug engaging surface and alocking recess having an undercut defining an opposing recess ledgehaving a recess engaging surface and a lug stop opposite the recessundercut. The method of forming the thermoformed locking assemblyincludes providing a mold having a mold surface with a moveable lockinglug mold portion and a moveable locking recess mold portion. Each of themoveable locking lug mold portion and the moveable locking recess moldportion is moveable between a mold condition aligned with the moldsurface and a retracted condition below the mold surface. The moveablelocking lug mold portion has an upper surface with a cavity definedtherein corresponding in shape to at least a portion of the locking lug.The moveable locking lug mold portion has a lug undercut mold memberslidably mounted on an angled surface of the moveable locking lug moldportion with the lug undercut mold member having a flange correspondingto the lug undercut. The moveable locking recess mold portion has aprotrusion extending above the mold surface when the moveable lockingrecess mold portion is in the mold condition. The protrusion correspondsin shape to at least a portion of the locking recess. The moveablelocking recess mold portion has a recess undercut mold member slidablymounted on an angled surface of the moveable locking recess portion withthe recess undercut mold member having a flange corresponding to therecess undercut.

The method includes positioning at least one web of thermoformablematerial on the mold surface with a first web portion proximate themoveable locking lug mold portion and a second web portion proximate themoveable locking recess mold portion and with both the moveable lockinglug mold portion and moveable locking recess mold portion in the moldcondition. For example, a single web can be positioned on both themoveable locking lug mold portion and the moveable locking recess moldportion if a single piece construction is desired. Alternatively,separate webs can be positioned on the moveable locking lug mold portionand moveable locking recess mold portion, respectively, if a two-piececonstruction is preferred. As disclosed in further detail, a web of lessthickness can be used due to the mold of the disclosed subject matter.The method further includes thermoforming the at least one web to forman article including a locking lug and a locking recess. The locking lughas an undercut defining a cantilevered lug ledge having a lug engagingsurface formed by the moveable locking lug mold portion. The lockingrecess has an undercut defining an opposing recess ledge having a recessengaging surface and a lug stop opposite the recess undercut formed bythe moveable locking recess mold portion. The method further includesretracting the moveable locking lug mold portion and the moveablelocking recess mold portion to the retracted condition. The lug undercutmold member slides along the angled surface of the moveable locking lugmold portion to release the lug undercut when the moveable locking lugmold portion is moved towards the retracted condition. The recessundercut mold member slides along the angled surface of the moveablelocking recess mold portion to release the recess undercut when themoveable locking recess mold portion is moved towards the retractedcondition.

Additionally, and as embodied herein, the lug undercut mold member canbe biased towards an initial position. The lug undercut mold member canslide along the angled surface of the moveable locking lug mold portionagainst the bias until the lug undercut is released returning the lugundercut mold member to the initial position.

Furthermore, and as embodied herein, the recess undercut mold member canbe biased towards an initial position. The recess undercut mold membercan slide along the angled surface of the moveable locking recess moldportion against the bias until the recess undercut is released returningthe recess undercut mold member to the initial position.

In accordance with another aspect of the disclosed subject matter, athermoformed locking assembly is provided. The thermoformed lockingassembly comprises a locking lug and a locking recess having one or moreof the features set forth above, and as further described in detailherein.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and are intended toprovide further explanation of the disclosed subject matter claimed.

The accompanying drawings, which are incorporated in and constitute partof this specification, are included to illustrate and provide a furtherunderstanding of the method and system of the disclosed subject matter.Together with the description, the drawings serve to explain theprinciples of the disclosed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 is a plan view of an exemplary embodiment of a container inaccordance with the disclosed subject matter in an open position.

FIG. 2 is a perspective view of another exemplary embodiment of acontainer in accordance with the disclosed subject matter in an openposition.

FIG. 3A is a bottom perspective view of an exemplary locking lug andrecess of the container of FIG. 2 in a closed position.

FIG. 3B is a top perspective view of the locking lug and recess of thecontainer of FIG. 3A in the closed position.

FIG. 4A is a perspective view of another exemplary locking lug inaccordance with the disclosed subject matter, a complementary lockingrecess (not shown) being a mirror image of the locking lug.

FIG. 4B is a perspective view of another exemplary locking lug inaccordance with the disclosed subject matter, a complementary lockingrecess (not shown) being a mirror image of the locking lug.

FIG. 5A is a perspective view of the locking lug of FIG. 4A, showing afinite element analysis to illustrate additional details of the lockinglug in accordance with the disclosed subject matter.

FIG. 5B is a perspective view of the locking lug of FIG. 4B, showing afinite element analysis to illustrate additional details of the lockinglug in accordance with the disclosed subject matter.

FIG. 6A is a perspective view of the locking lug of FIG. 4A, showing afinite element analysis to illustrate additional details of the lockinglug in accordance with the disclosed subject matter.

FIG. 6B is a perspective view of the locking lug of FIG. 4B, showing afinite element analysis to illustrate additional details of the lockinglug in accordance with the disclosed subject matter.

FIG. 7A is a perspective view of the locking lug of FIG. 4A, showing afinite element analysis to illustrate additional details of the lockinglug in accordance with the disclosed subject matter.

FIG. 7B is a perspective view of the locking lug of FIG. 4B, showing afinite element analysis to illustrate additional details of the lockinglug in accordance with the disclosed subject matter.

FIG. 8A is a perspective view of the locking lug of FIG. 4A, showing afinite element analysis to illustrate additional details of the lockinglug in accordance with the disclosed subject matter.

FIG. 8B is a perspective view of the locking lug of FIG. 4B, showing afinite element analysis to illustrate additional details of the lockinglug in accordance with the disclosed subject matter.

FIG. 9 is a schematic view of another exemplary embodiment of a lockinglug and locking recess in accordance with the disclosed subject matter.

FIG. 10 is a schematic view of another exemplary embodiment of a lockinglug and locking recess in accordance with the disclosed subject matter.

FIG. 11A is a schematic view of another exemplary embodiment of alocking lug of a container in a stacking engagement with a locking lugof another container in accordance with the disclosed subject matter.

FIG. 11B is a schematic view of another exemplary embodiment of alocking lug of a container in a stacking engagement with a locking lugof another container in accordance with the disclosed subject matter.

FIG. 12 is a perspective view of the container of FIG. 1 in a closedposition, with portions cut away to show an exemplary locking lug inengagement with an exemplary locking recess in accordance with thedisclosed subject matter.

FIG. 13A is a diagram illustrating additional details of exemplarylocking lugs and locking recesses, including exemplary open/close lockforce, average weight and material thickness.

FIG. 13B is a diagram illustrating additional details of exemplarylocking lugs and locking recesses, including exemplary open/close lockforce, average weight and material thickness.

FIG. 13C is a schematic illustrating additional exemplary configurationsfor locking lugs and locking recesses in accordance with the disclosedsubject matter.

FIG. 14 is a perspective view of an exemplary mold for forming acontainer having a locking lug and a locking recess in accordance withthe disclosed subject matter.

FIG. 15A is an enlarged perspective view of the exemplary mold of FIG.14 , showing additional details of a locking lug mold portion and alocking recess mold portion in accordance with the disclosed subjectmatter.

FIG. 15B is a cross-sectional view taken along line B-B of FIG. 15A.

FIG. 15C is an enlarged cross-sectional view of region C of FIG. 15B.

FIG. 16 is a schematic view of an exemplary locking lug mold portion andlocking recess mold portion of an exemplary mold in accordance with thedisclosed subject matter.

DETAILED DESCRIPTION

The apparatus and methods presented herein may be used for storage,transportation, and display of various products, such as food items andother perishable and nonperishable products. The disclosed subjectmatter is particularly suited for storage, transportation, and displayof food items, wherein the container lid and base provide a lockingassembly to allow easy locking and release of the lid.

In accordance with the disclosed subject matter, as embodied and broadlydescribed, the disclosed subject matter includes a thermoformedcontainer including a base having a base flange and a lid having a lidflange. The lid is configured to be moved relative to the base between aclosed position and an open position. For example, and as set forth indetail below, the lid can be hingedly connected to the base to form acontainer with one-piece construction, or the lid can be a separatemember to form a container with two-piece construction if preferred. Thelid flange is adjacent to the base flange when in the closed position.At least one of the base flange or the lid flange is formed to include alocking lug having a lug undercut defining a cantilevered lug ledgehaving a lug engaging surface. The other of the base flange or lidflange is formed to include a locking recess having a recess undercutdefining an opposing recess ledge having a recess engaging surface and alug stop opposite the recess undercut. The locking recess is aligned toreceive the locking lug and the lug stop is configured to position thelocking lug in the locking recess to define a locking assembly inaccordance with the disclosed subject matter, such that the lug engagingsurface is in engagement with the recess engaging surface when the baseand lid are in the closed position.

Reference will now be made in detail to the various exemplaryembodiments of the disclosed subject matter, exemplary embodiments ofwhich are illustrated in the accompanying drawings. The structure andcorresponding methods of operation of the disclosed subject matter willbe described in conjunction with the detailed description of thesystems.

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separateviews, serve to further illustrate various embodiments and to explainvarious principles and advantages all in accordance with the disclosedsubject matter. For purpose of explanation and illustration, and notlimitation, exemplary embodiments of the container, and of the lockingassembly, in accordance with the disclosed subject matter are shown inFIGS. 1-16 . The container is suitable for use with a wide variety ofperishable and nonperishable products. For example, and withoutlimitation, the container can be used for shipping, serving, storing,preparing and/or re-using food items, such as an egg carton for eggs ora cake container for cakes.

For purpose of illustration, and not limitation, reference is now madeto FIGS. 1 and 2 illustrating a thermoformed container 100, according toan exemplary embodiment of the disclosed subject matter. As embodiedherein, the thermoformed container 100 includes a base 101 having a baseflange 111 and a lid 102 having a lid flange 112. The base flange 111and the lid flange 112 can extend outwardly from the base 101 and thelid 102, respectively. At least one of the base flange 111 or lid flange112 is formed to include a locking lug 121. The locking lug 121 has alug undercut 131 defining a cantilevered lug ledge having a lug engagingsurface 141. The other of the base flange 111 or the lid flange 112 isformed to include at least one locking recess 122. The locking recess122 has a recess undercut 132 defining an opposing recess ledge having arecess engaging surface 142 and a lug stop 192 opposite the recess undercut 132. For purpose of explanation and illustration, and notlimitation, as embodied herein, the thermoformed container 100 can havetwo locking lugs 121 each disposed proximate a corner of the base flange111, and two locking recesses 122 each disposed in a correspondingcorner of the lid flange 112. As described herein, locking recess 122 isaligned to receive locking lug 121 and lug stop 192 is configured toposition the locking lug 121 with the lug engaging surface 141 inengagement with the recess engaging surface 142 when the lid is movedinto the closed position.

The lid 102 is configured to be moved relative to the base 101 between aclosed position and an open position. Reference is now made to FIGS. 3Aand 3B, the base 101 and lid 102 are shown in a closed position. The lidflange 112 is adjacent to the base flange 111 when the base 101 and thelid 102 are in the closed position. The locking recess 122 is aligned toreceive the locking lug 121 such that the lug engaging surface 141 is inengagement with the recess engaging surface 142 when the base 101 andlid 102 are in the closed position.

Reference is now made to FIG. 12 , showing lug stop 192 opposite therecess undercut 132. Lug stop 192 can be configured to position thelocking lug in the locking recess with the lug engaging surface inengagement with the recess engaging surface when the lid is moved intothe closed position. The lug stop 192 can be configured such that littleor no clearance is provided at the back of the locking lug 121 when thelid is moved into the closed position with the cantilevered lug ledgepositioned under the undercut of the opposing locking recess ledge andthe lug engaging surface in engagement with the recess engaging surface.As further embodied herein, the lug stop 192 can reduce or preventmovement and inadvertent release of the locking lug 121 from the lugrecess 122 when in the closed position. For purpose of example and notlimitation, lug stop 192 can be made vertical to facilitate molding ofthe locking recess.

Additionally, and as embodied herein, the lid 102 can be hingedlyconnected to the base 101 by a hinge 105. The hinge 105 can be disposedon an opposite side of the container as the locking lug 121 and lockingrecess 122. Alternatively, as further embodied herein, the base 101 andthe lid 102 can be configured to allow removal of the lid 102 when thelid is moved to the open position, such as by providing a frangiblehinge to tear off the lid 102 from the base 101, or by forming the base101 and lid 102 as separate members. Furthermore, a plurality of lockinglugs 121 and a corresponding plurality of locking recesses 122 can beprovided. For example, if the lid 102 is hingedly connected to the base101 to form a one-piece construction, two locking lugs 121 and twolocking recesses 122 can be provided, such as disposed on an oppositeside of the container as the hinge 105. Alternatively, if a two-piececonstruction is desired, a plurality of locking lugs 121 andcorresponding locking recesses 122 can be provided, such as disposed ateach corner of the container and/or along one or more edges.

Furthermore, and as embodied herein, a minimum closing force can beapplied to move the lid 102 into the closed position with the lugengaging surface 141 in engagement with the recess engaging surface 142,and a minimum opening force can be applied to move the lug engagingsurface 141 out of engagement with the recess engaging surface 142. Theminimum opening force can be greater than the minimum closing force.

Reference is now made to FIGS. 4A and 4B, the locking lug 121 caninclude stiffening ribs 151 along two sides of the locking lug 121 toprovide additional support to the undercut 131, according to an aspectof the disclosed subject matter. Similarly, locking recess 122 likewisecan include stiffening ribs along two sides of the locking recess. Asembodied herein, both the lug and recess are provided with stiffeningribs, such that the desired minimum opening and closing forces are lesssensitive to material thickness of the web since the ribs minimizedeflection of the lug and recess. As additionally embodied herein, thelocking lug 121 can be generally L-shaped in cross section. Furthermore,and as evident from the figures, the locking lug can be provided with asingle-sided configuration, wherein a lug undercut is provided only onone side of the locking lug (e.g., on a front side of the lug).Similarly, the locking recess can be single-sided with the recessundercut on one side of the locking recess. In this manner, the lockinglug and recess can be provided in a relatively small space, so as to beincorporated on containers of smaller size and reduced web thickness,without compromising the integrity of the minimum closing and openingforces as desired.

Reference is now made to FIGS. 5A-6B, a finite element test, applying adownward force to the exemplary locking lugs of FIGS. 4A and 4B, isshown for purpose of illustration and comparison, showing a locking lug121 without stiffening ribs (FIGS. 5A and 6A) and with stiffening ribs151 (FIGS. 5B and 6B), in accordance with the disclosed subject matter.

Reference is now made to FIGS. 7A-8B, a finite element test, applying anupward (pry-up) force to the exemplary locking lugs of FIGS. 4A and 4B,is shown for purpose of illustration and comparison, showing a lockinglug 121 without stiffening ribs (FIGS. 7A and 8A) and with stiffeningribs 151 (FIGS. 7B and 8B), in accordance with the disclosed subjectmatter.

Reference is now made to FIGS. 9-11B, the lug undercut 131 and recessundercut 132 can define a cantilevered lug ledge and an opposing recessledge, respectively, and each of the cantilevered lug ledge and opposingrecess ledge can have an outer edge 133, 134, respectively, according toan aspect of the disclosed subject matter. As further embodied herein,outer edges 133 or 134 can be configured to reduce or maintain theminimum closing force required to move the lid into the closed positionas desired. For purpose of example and not limitation, outer edges 133or 134 can be rounded, chamfered, or chord shaped. Furthermore, and asembodied herein, locking lug 121 can include ramps 161, 162, which canallow for more efficient stacking of containers 100 when in the openposition. Further referencing FIGS. 11A and 11B, Stack Height A 302 ofcontainers 100 without ramps 161 and 162 and Stack Height B 303 ofcontainers with ramps 161 and 162 are shown. For purpose of example andnot limitation, Stack Height B 303 can be less than Stack Height A 302.As further embodied herein, ramps 161 and 162 can be formed at angle301. For purposes of example and not limitation, containers 100 can beformed such that angle 301 is approximately 30 degrees and Stack HeightB 303 is approximately 0.124 inches or less.

Reference is now made to FIGS. 13A and 13B, diagrams illustratingopening and closing forces to move the lid 102 and the base 101 betweenan open and closed position are provided for different materialthicknesses. As shown in FIGS. 13A and 13B, a lower closing force thanopening force can be achieved using the locking lugs and locking membersof the disclosed subject matter, which can allow for easy filed packing,maintaining a closed container during shipping and a secure yet easycontainer to open when consuming the food product. FIGS. 13A and 13Bfurther show a range of PET sheet gauges for purpose of illustration andconfirmation of the disclosed subject matter. As shown, sheet gauges canbe used from 18-mil down to 15.5-mil, and the containers were formedwithout any container stripping issues experienced with previous downgauge trials with button, bar and bone button lock geometries. Thecontainers formed according to the disclosed subject matter can thusclose easily with less than 1-lb. force, provide an audible click whenthe lock engages and stay securely locked with greater than 2.5 lbs.force to open.

As shown in FIG. 13A, for purpose of illustration and not limitation,opening and closing forces for exemplary containers in accordance withthe disclosed subject matter are illustrated. Container B formed havinga material thickness of 15.5 mil provided a closing force of about 0.871lbs. and an opening force of about 1.666 lbs. Container B formed havinga material thickness of 16.0 mil provided a closing force of about 0.928lbs. and an opening force of about 1.713 lbs. Container B formed havinga material thickness of 16.5 mil provided a closing force of about 1.346lbs. and an opening force of about 1.687 lbs. Container B formed havinga material thickness of 17.0 mil provided a closing force of about 0.972lbs. and an opening force of about 1.944 lbs. Container B formed havinga material thickness of 17.5 mil provided a closing force of about 0.585lbs. and an opening force of about 2.090 lbs. For purpose ofillustration and not limitation, an exemplary container (“container C”)having a locking lug and locking recess in accordance with the disclosedsubject matter. Container C formed having a material thickness of 15.5mil provided a closing force of about 0.6 lbs. and an opening force ofabout 1.45 lbs. Container C formed having a material thickness of 16.0mil provided a closing force of about 0.55 lbs. and an opening force ofabout 1.55 lbs. Container C formed having a material thickness of 16.5mil provided a closing force of about 1 lb. and an opening force ofabout 1.55 lbs. Container C formed having a material thickness of 17.0mil provided a closing force of about 1.1 lbs. and an opening force ofabout 1.9 lbs. Container C formed having a material thickness of 17.5mil provided a closing force of about 1.15 lbs. and an opening force ofabout 1.8 lbs.

As shown in FIG. 13B, for purpose of illustration and not limitation,opening and closing forces for an exemplary container (“container B”) inaccordance with the disclosed subject matter are illustrated. ContainerB formed having a material thickness of 16.0 mil provided a closingforce of about 1.32 lbs. and an opening force of about 1.93 lbs.Container B formed having a material thickness of 16.5 mil provided aclosing force of about 1.29 lbs. and an opening force of about 2.46 lbs.Container B formed having a material thickness of 17.0 mil provided aclosing force of about 1.10 lbs. and an opening force of about 2.05 lbs.Container B formed having a material thickness of 17.5 mil provided aclosing force of about 1.42 lbs. and an opening force of about 2.48 lbs.Container B formed having a material thickness of 18.0 mil provided aclosing force of about 1.39 lbs. and an opening force of about 2.51 lbs.

As shown in FIG. 13C, for purpose of illustration and not limitation,exemplary locking members in accordance with the disclosed subjectmatter are illustrated. For example and not limitation, an exemplarylocking member (“Latch A”) can have an engaging surface with a dimensionw₁ within a range of about 0.053 in to about 0.062 in. As embodiedherein, Latch A can have a locking lug dimension h₁ of about 0.170 inand a locking lug dimension h₂ of about 0.180 in. For example and notlimitation, an exemplary locking member (“Latch B”) can have an engagingsurface with a dimension w₁ within a range of about 0.048 in to about0.057 in. As embodied herein, Latch B can have a locking lug dimensionh₁ of about 1.170 in and a locking lug dimension h₂ of about 0.180 in.For example and not limitation, an exemplary locking member (“Latch C”)can have an engaging surface with a dimension w₁ within a range of about0.043 in to about 0.052 in. As embodied herein, Latch C can have alocking lug dimension h₁ of about 0.170 in and a locking lug dimensionh₂ of about 0.180 in.

Hence, as evident from the above, a container having the locking lug andrecess arrangement of the disclosed subject matter can be provided withreduced material web thickness and reduced flange size withoutcompromising the integrity of the desired minimum closing and openingforces.

In accordance with another aspect of the disclosed subject matter, amethod of forming a thermoformed locking assembly, or article, such as acontainer, having such locking assembly, is provided. The thermoformedlocking assembly includes a locking lug having an undercut defining acantilevered lug ledge having a lug engaging surface and a lockingrecess having an undercut defining an opposing recess ledge having arecess engaging surface and a lug stop opposite the recess undercut. Themethod of forming the thermoformed locking assembly includes providing amold having a mold surface with a moveable locking lug mold portion anda moveable locking recess mold portion. The mold surface can be a singleassembly with both the moveable locking lug mold portion and themoveable locking recess mold portion, or the mold surface can includeseparate assemblies for each of the locking lug mold portion and lockingrecess mold portion respectively, such as if a two-piece construction isdesired. Each of the moveable locking lug mold portion and the moveablelocking recess mold portion are moveable between a mold conditionaligned with the mold surface and a retracted condition below the moldsurface. The moveable locking lug mold portion has an upper surface witha cavity defined therein corresponding in shape to at least a portion ofthe locking lug. The moveable locking lug mold portion has a lugundercut mold member slidably mounted on an angled surface of themoveable locking lug mold portion with the lug undercut mold memberhaving a flange corresponding to the lug undercut. The moveable lockingrecess mold portion has a protrusion extending above the mold surfacewhen the moveable locking recess mold portion is in the mold condition.The protrusion corresponds in shape to at least a portion of the lockingrecess. The moveable locking recess mold portion has a recess undercutmold member slidably mounted on an angled surface of the moveablelocking recess portion with the recess undercut mold member having aflange corresponding to the recess undercut.

The method further includes positioning at least one web ofthermoformable material on the mold surface with the moveable lockinglug mold portion and the moveable locking recess mold portion each inthe mold condition, such that a first web portion is proximate themoveable locking lug mold portion and a second web portion is proximatethe moveable locking recess mold portion. For example, a single web canbe positioned on both the moveable locking lug mold portion and themoveable locking recess mold portion if a single piece construction isdesired. Alternatively, separate webs can be positioned on the moveablelocking lug mold portion and moveable locking recess mold portionrespectively if a two-piece construction is preferred. As noted above, aweb of reduced thickness can be used due to the mold of the disclosedsubject matter. The method further includes thermoforming the at leastone web to form an article including a locking lug and a locking recess.The locking lug has an undercut defining a cantilevered lug ledge havinga lug engaging surface formed by the moveable locking lug mold portion.The locking recess has an undercut defining an opposing recess ledgehaving a recess engaging surface and a lug stop opposite the recessundercut formed by the moveable locking recess mold portion. The methodfurther includes retracting the moveable locking lug mold portion andthe moveable locking recess mold portion to the retracted condition. Thelug undercut mold member slides along the angled surface of the moveablelocking lug mold portion to release the lug undercut when the moveablelocking lug mold portion is moved towards the retracted condition. Therecess undercut mold member slides along the angled surface of themoveable locking recess mold portion to release the recess undercut whenthe moveable locking recess mold portion is moved towards the retractedcondition.

Reference is now made to FIGS. 14-15C illustrating a mold 200 forforming the thermoformed container 100, according to an aspect of thedisclosed subject matter. The mold 200 has a mold surface 201 with amoveable locking lug mold portion 211 and a moveable locking recess moldportion 212. Each of the moveable locking lug mold portion 211 andmoveable locking recess mold portion 212 is moveable between a moldcondition aligned with the mold surface 201 and a retracted conditionbelow the mold surface 201. The moveable locking lug mold portion 211has an upper surface with a cavity 231 defined therein corresponding inshape to at least a portion of the locking lug 121. The moveable lockinglug mold portion 211 has a lug undercut mold member 221 slidably mountedon an angled surface 251 of the moveable locking lug mold portion 211with the lug undercut mold member 221 having a flange 261 correspondingto the lug undercut 131.

The moveable locking recess mold portion 212 has a protrusion 232extending above the mold surface 201 when the moveable locking recessmold portion 212 is in the mold condition. The protrusion 232corresponds in shape to at least a portion of the locking recess 122.The moveable locking recess mold portion 212 has a recess undercut moldmember 222 slidably mounted on an angled surface 252 of the moveablelocking recess portion 212 with the recess undercut mold member 222having a flange 262 corresponding to the recess undercut 132.

For purpose of illustration and not limitation, as embodied herein, amethod of forming container 100 includes positioning at least one web ofthermoformable material on the mold surface 201 with the moveablelocking lug mold portion 211 and the moveable locking recess moldportion 212 each in the mold condition. The method includesthermoforming the at least one web to form an article including alocking lug 121 and a locking recess 122. The locking lug 121 has a lugundercut 131 defining a cantilevered lug ledge having a lug engagingsurface 141 formed by the moveable locking lug mold portion 211. Thelocking recess 122 has a recess undercut 132 defining an opposing recessledge having a recess engaging surface 142 and a lug stop 192 oppositethe recess undercut formed by the moveable locking recess mold portion212. The method includes retracting the moveable locking lug moldportion 211 and the moveable locking recess mold portion 212 to theretracted condition. The lug undercut mold member 221 slides along theangled surface 251 of the moveable locking lug mold portion 211 torelease the lug undercut 131 when the moveable locking lug mold portion211 is moved towards the retracted condition. The recess undercut moldmember 222 slides along the angled surface 252 of the moveable lockingrecess mold portion 212 to release the recess undercut 132 when themoveable locking recess mold portion 212 is moved towards the retractedcondition. Additional features of the locking lug and locking recess asset forth above can be incorporated with the method as desired.

Additionally, and as embodied herein, the lug undercut mold member 221can be biased towards an initial position, and the lug undercut moldmember 221 can slide along the angled surface 251 of the moveablelocking lug mold portion 211 against the bias until the lug undercut 131is released returning the lug undercut mold member 221 to the initialposition. Additionally or alternatively, as embodied herein, the recessundercut mold member 222 can be biased towards an initial position, andthe recess undercut mold member 222 can slide along the angled surface252 of the moveable locking recess mold portion 212 against the biasuntil the recess undercut 132 is released returning the recess undercutmold member 222 to the initial position.

Furthermore, and as embodied herein, the mold 200 can include a malelock assembly pocket 282 and a female lock assembly pocket 281, whichcan be configured to secure the web of thermoplastic material to themold 200.

With reference to FIG. 15C, for purpose of illustration and notlimitation, the moveable locking recess mold portion 212 has alongitudinal dimension of “B” and the flange 262 of recess undercut moldmember 222 has a longitudinal dimension of “A,” and as embodied herein,B is greater than A.

Reference is now made to FIG. 16 illustrating the moveable lockingrecess mold portion 212 and the moveable locking lug mold portion 211 inan engaged position, which can be used to determine tolerances for themold 200.

For example, compact locking lugs (e.g., male locks) and lockingrecesses (e.g., female locks) were formed into the base and lid of acontainer and sized to minimally impinge on internal volume of theclamshell with sufficient engagement of the locking lug and lockingrecess engagement surfaces, created by undercuts in the locking lug andlocking recess features, to secure the container closed after thecontainer is filled, thus creating sufficient lock engagement to keepthe container closed during handling and transportation, while stillallowing the container to be opened easily. As such, a container can beformed having a minimum opening force and minimum closing force suchthat the minimum opening force is greater than the minimum closingforce. For purposes of example and not limitation, a container soconfigured can allow the container to stay closed while handled andshipped to an end-user location.

Molds according to the disclosed subject matter, including the moveablelocking lug mold portion and moveable locking recess mold portion, canallow the formation of a sufficient undercut in the locking lug and thelocking recess while still allowing the web of thermoformed material tostrip easily from the mold surface. It can be desirable to use thinnerwebs of thermoformable material for cost-saving purposes, however, whenthinner webs are used, the locking lug and locking recess can requirelarger undercuts to provide more engagement between the engagementsurfaces of the locking lug and locking recess to keep the containerclosed. This added engagement can make it difficult to remove thelocking lug and locking recess from the mold at the undercuts withoutdamaging the locks.

With the movable retracting mold geometry and mechanism as disclosed andembodied herein, the locking lug and locking recess undercuts can beremoved from the mold when thinner webs are used. For example, themovable locking lug mold portion can include a lug undercut mold memberthat can be biased towards an initial position and that can slide alongan angled surface of the moveable locking lug mold portion, which canallow the lug undercut mold member to release the web from the moldwithout damaging or deforming the thermoformed web. Similarly, themovable locking recess mold portion can include a recess undercut moldmember that can be biased towards an initial position and that can slidealong an angled surface of the moveable locking recess mold portion,which can allow the recess undercut mold member to release the web fromthe mold without damaging or deforming the thermoformed web.

As the geometry of the locking lug and locking recess gets smaller, itcan be more difficult to form the undercut geometry, and the smallerlocking lug and locking recess undercut geometry can have lessengagement. As such, and as embodied herein, a stiffening rib can makethermoforming the locking lug and locking recess easier and morecontrollable and can provide stronger engagement as thinner webs areused for material savings purposes.

Additionally, and as embodied herein, a mold with a moveable locking lugmold portion and a moveable locking recess mold portion as describedfurther herein can allow thermoformed locking lugs and locking recessesto be released from the mold as the moveable locking lug mold portionand moveable locking recess mold portion can retract during partejection. For example, locking assemblies made according to the methodsdisclosed herein can have small geometry that can fit into a corner of ahinged container and can be easily manufactured. As further embodiedherein, the moveable locking lug mold portion and moveable lockingrecess mold portion can release the undercuts after molding.

As embodied herein, low stack height geometry can provide high packagingcube efficiency. Additionally, and as described further herein, thelocking lug and locking recess geometry can provide a differential inclosing and opening force of a container such that the container can beeasier to close and slightly harder to open. This can make it easier tofield pack containers and close the containers under low close force.The containers can stay closed and not open during shipment, and canrequire additional force to open during use of the container contents.

While the disclosed subject matter is described herein in terms ofcertain preferred embodiments, those skilled in the art will recognizethat various modifications and improvements can be made to the disclosedsubject matter without departing from the scope thereof. Moreover,although individual features of one embodiment of the disclosed subjectmatter can be discussed herein or shown in the drawings of the oneembodiment and not in other embodiments, it should be apparent thatindividual features of one embodiment can be combined with one or morefeatures of another embodiment or features from a plurality ofembodiments.

In addition to the specific embodiments claimed below, the disclosedsubject matter is also directed to other embodiments having any otherpossible combination of the dependent features claimed below and thosedisclosed above. As such, the particular features presented in thedependent claims and disclosed above can be combined with each other inother manners within the scope of the disclosed subject matter such thatthe disclosed subject matter should be recognized as also specificallydirected to other embodiments having any other possible combinations.Thus, the foregoing description of specific embodiments of the disclosedsubject matter has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit thedisclosed subject matter to those embodiments disclosed.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the method and system of thedisclosed subject matter without departing from the spirit or scope ofthe disclosed subject matter. Thus, it is intended that the disclosedsubject matter include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A method of forming a thermoformed lockingassembly including a locking lug having a lug undercut defining acantilevered lug ledge having a lug engaging surface and a lockingrecess having a recess undercut defining an opposing recess ledge havinga recess engaging surface and a lug stop opposite the recess undercut,the method comprising: providing a mold having a mold surface with amoveable locking lug mold portion and a moveable locking recess moldportion, each of the moveable locking lug mold portion and the moveablelocking recess mold portion being moveable between a mold conditionaligned with the mold surface and a retracted condition below the moldsurface, the moveable locking lug mold portion having an upper surfacewith a cavity defined therein corresponding in shape to at least aportion of the locking lug, and a lug undercut mold member slidablymounted on an angled surface of the moveable locking lug mold portionwith the lug undercut mold member having a flange corresponding to thelug undercut, and the moveable locking recess mold portion having aprotrusion extending above the mold surface when the moveable lockingrecess mold portion is in the mold condition and corresponding in shapeto at least a portion of the locking recess, and a recess undercut moldmember slidably mounted on an angled surface of the moveable lockingrecess portion with the recess undercut mold member having a flangecorresponding to the recess undercut; positioning at least one web ofthermoformable material having a first web portion on the mold surfacewith the moveable locking lug mold portion and a second web portion onthe mold surface with the moveable locking recess mold portion each inthe mold condition; thermoforming the web to form an article including alocking lug having an undercut defining a cantilevered lug ledge havinga lug engaging surface formed by the moveable locking lug mold portionand a locking recess having an undercut defining an opposing recessledge having a recess engaging surface and a lug stop opposite therecess undercut formed by the moveable locking recess mold portion; andretracting the moveable locking lug mold portion and the moveablelocking recess mold portion to the retracted condition, wherein whileretracting the lug undercut mold member slides along the angled surfaceof the moveable locking lug mold portion to release the lug undercut andthe recess undercut mold member slides along the angled surface of themoveable locking recess mold portion to release the recess undercut. 2.The method of forming a thermoformed locking assembly of claim 1,wherein the locking lug of the article formed is L-shaped in crosssection.
 3. The method of forming a thermoformed locking assembly ofclaim 1, wherein the lug engagement surface of the article formed has adepth of between approximately 0.043 inches and 0.063 inches.
 4. Themethod of forming a thermoformed locking assembly of claim 1, whereinthe lug undercut mold member is biased towards an initial position, thelug undercut mold member slides along the angled surface of the moveablelocking lug mold portion against the bias until the lug undercut isreleased returning the lug undercut mold member to the initial position.5. The method of forming a thermoformed locking assembly of claim 1,wherein the recess undercut mold member is biased towards an initialposition, the recess undercut mold member slides along the angledsurface of the moveable locking recess mold portion against the biasuntil the recess undercut is released returning the recess undercut moldmember to the initial position.
 6. The method of forming a thermoformedcontainer of claim 1, wherein the mold includes a male lock assemblypocket and a female lock assembly pocket, configured to secure the webof thermoformable material to the mold surface.
 7. A method of forming athermoformed locking assembly including a locking lug having a lugundercut defining a cantilevered lug ledge having a lug engaging surfaceand a locking recess having a recess undercut defining an opposingrecess ledge having a recess engaging surface and a lug stop oppositethe recess undercut, the method comprising: providing a mold having amold surface with a moveable locking lug mold portion and a moveablelocking recess mold portion, each of the moveable locking lug moldportion and the moveable locking recess mold portion being moveablebetween a mold condition aligned with the mold surface and a retractedcondition below the mold surface, the moveable locking lug mold portionhaving an upper surface with a cavity defined therein corresponding inshape to at least a portion of the locking lug, and a lug undercut moldmember slidably mounted on an angled surface of the moveable locking lugmold portion with the lug undercut mold member having a flangecorresponding to the lug undercut, and the moveable locking recess moldportion having a protrusion extending above the mold surface when themoveable locking recess mold portion is in the mold condition andcorresponding in shape to at least a portion of the locking recess, anda recess undercut mold member slidably mounted on an angled surface ofthe moveable locking recess portion with the recess undercut mold memberhaving a flange corresponding to the recess undercut; positioning atleast one web of thermoformable material having a first web portion onthe mold surface with the moveable locking lug mold portion and a secondweb portion on the mold surface with the moveable locking recess moldportion each in the mold condition; and thermoforming the web to form anarticle including a locking lug having an undercut defining acantilevered lug ledge having a lug engaging surface formed by themoveable locking lug mold portion and a locking recess having anundercut defining an opposing recess ledge having a recess engagingsurface and a lug stop opposite the recess undercut formed by themoveable locking recess mold portion.